R/prune.itree.R

In itree: Tools for classification and regression trees, with an emphasis on interpretability.

#ALG: itree copies this direclty from rpart.

#SCCS @(#)prune.rpart.s	1.9 10/30/01
prune.itree <- function(tree, cp, ...)
{
    ff <- tree$frame
    id <- as.integer(row.names(ff))
    toss <- id[ff$complexity <= cp &  ff$var!='<leaf>']#not a leaf
    if (length(toss)==0) return(tree)   #all the tree is retained

    newx <- snip.itree(tree, toss)

    ## Now cut down the CP table
    temp <- pmax(tree$cptable[,1L], cp)
    keep <- match(unique(temp), temp)
    newx$cptable <- tree$cptable[keep,,drop=FALSE]
    newx$cptable[max(keep),1L] <- cp

    newx
}